THE large gang of thugs milling with bamboo spears in the main street of Menteng, Jakarta's most fashionable old-money district, said it all.
Calling themselves the Benteng Demokrasi Rakyat, or People's Democratic Front, they began by handing out miniature red-and-white Indonesian flags, the kind sold by hawkers at city intersections for as little as 1000 rupiah (12c).
With cute logic, the group's name abbreviates to bendera, or flag.
But as the traffic backed up on Jalan Diponegoro - the leafy central thoroughfare named after a hero of Javanese anti-colonial history, a folk warrior-cum-robber and killer with a shady reputation not unlike those of Robin Hood or Ned Kelly - things turned ugly.
Fuelled by weeks of anti-Malaysian rhetoric in the Indonesian media, the Bendera bovver boys started demanding ID cards from the cars' occupants. Every resident in the country, citizen or not, is required by law to carry one.
The gang, part of a floating mass of Jakarta youths generally available for affiliation with whoever pays the most, was looking for Malaysians - people with essentially the same racial features as themselves, only with allegiance to a different flag.
They didn't find any, and eventually police moved them on without making arrests, but it was enough to prompt President Susilo Bambang Yudhoyono to call for calm two days later.
Speaking after a cabinet meeting on Thursday, Dr Yudhoyono said there was "no need to take excessive action ... this is Ramadan, when the majority of our people are fasting. Why should there be violent acts?"
Not since the belligerent nationalist Sukarno rallied Indonesians around the standard of anti-Malaysian sentiment, with his spectacularly pointless konfrontasi pseudo-war in Borneo in the early 1960s, has there been vitriol of the sort seen over recent months.
Coincidentally, the Bendera gang has an office in the former headquarters of the Indonesian Democratic Party for Struggle - the vehicle of Sukarno's daughter, Megawati Sukarnoputri, which performed dismally in July's presidential elections.
When Dr Yudhoyono and his incoming deputy, respected economist Boediono, are sworn in as the heads of the country's new government late next month, Ms Megawati will be standing on the sidelines, still trying to work out how to wield influence in an administration that has little use for her. The notion of standing as a coherent and productive political opposition in the national parliament seems anathema to Ms Megawati or anyone else, in a body politic largely made up of elites and their offspring still clinging to the belief they were born to rule.
But in the meantime a rolling series of disputes over Malaysians "thieving" Indonesian culture have been giving a thrill of the xenophobic sentiment with which Ms Megawati's father and others helped to forge the idea of a united Indonesia after the former Dutch colonists fled in 1949.
The latest flare-ups included accusations by a state music company executive in Solo, Central Java, that Malaysia's national anthem was a rip-off of a song written in Indonesia.
The anthem - Negaraku, or My Country - sounded too much like a tune written and recorded by the Bandung Ensemble on Sukarno's orders in 1956, a year before Malaysia won independence from Britain, the executive claimed. And outrage was sparked last month by the apparent appropriation of a sacred Balinese temple dance, known as the Pendet, by Malaysia's tourism authority.
In both cases, reality seems to have been lurking well behind the gloom of popular perception. The Pendet dance issue was a case of an independent television production house showing its profound cultural ignorance, hitching the Balinese cultural form to a documentary series on Malaysia without any sense of irony.
As for the national anthem, a prominent Indonesian musicologist was found who claimed that both it and the Indonesian ballad in question - Terang Bulan, or Moonlight - were derived from a 19th-century French song made popular in both colonies as well as in the former French dominion of the Seychelles. It appeared both Indonesia and Malaysia had been pipped to the post - by the French.
Other disputes have involved the ownership of Javanese dance forms and the angklung percussion pipe, batik printing (much of which is now done in China anyway) and a couple of islands off Kalimantan rich in oil and gas resources.
One university, in Semarang in Central Java, even announced it would cease allowing enrolments from Malaysians, prompting a Malaysian response that an Indonesian education probably wasn't worth bothering with.
It's true there is a genuine old-school antipathy between ordinary Indonesians and Malaysians, perhaps derived, ironically enough, from their broadly common culture.
Even the languages of each country come from the same root, classical Malay, although Bahasa Malaysia and Bahasa Indonesia have over decades developed significant enough differences that native speakers of one will happily deride those of the other for their poor command of the tongue.
In the view of some, Malaysia has a split personality over its ethnic identity, with the legal classifications between Chinese, Indian and Malay creating - as Kuala Lumpur-based Singaporean journalist Carolyn Hong put it this week - a "louder and at times poisonous" race rhetoric. That, she said, was due to domestic Malaysian political imperatives - in particular the weakening of the grip on power held by the ethnic Malay-based UMNO party. Hong cited the instance two weeks ago of Malays stomping on a cow's head to protest against the building of a Hindu temple.
Musni Umar, an Indonesian member of a bilateral board convened to thrash out problems between the two countries, put it succinctly: "It's not easy - most Malaysians come from Indonesia anyway."
When Malaysian Foreign Minister Datuk Anifah Aman visits Indonesia next week to discuss the downturn in relations, he might like to ask what Jakarta really thinks.